Stress may not be as bad for us as we think. In fact, facing stress early in life may make us better at handling difficult situations as adults. That is what a study on rats by scientists at the Tata Institute of Fundamental Research (TIFR) in Mumbai found.

TIFR neurobiologist Vidita Vaidya and her team induced stress in just-born rat pups by separating them from their mother for a few hours daily for two weeks. They found that the unpleasant event modified the brains of the animals in a such way that they could handle stressful events later in life better.

“It is not that we deprived them emotionally or nutritionally by keeping them away from mothers for long hours. The separation was only for some three hours a day — about the amount of time that their mothers would have spent away from the offspring foraging for food, if they were in the wild. But the impact we observed was dramatic,” says Vaidya, who joined TIFR in 2000.

“We could see a dramatic increase in certain growth factors that aid the production of neurons, a transient surge in the production of neurons and alteration in gene activity. All these seemed to be part of an overall strategy for cognitive improvement,” she says.

To establish this, the TIFR scientists pushed the animals into a pool. To avoid drowning, the animals had to swim to platforms located in different parts of the pool. The scientists found that the animals, which experienced stress earlier in life, performed the task better. “It was as if they swam with a purpose whereas others looked a bit confused,” she says.

“But the animals had to pay a price for this adaptive advantage. Their cognitive faculties declined much faster than animals that had a normal upbringing,” says Vaidya, lead author of a paper scheduled to appear in the journal Biological Psychiatry soon.

The general view has been that stress is really bad for you. “Transiently, what we found was that it helps the animals to do better on stress-associated tasks when they are young. But this improvement is only on the stress front, it doesn’t influence other neurological outcomes,” she says.

A look into the brains of the animals helped the scientists understand the reasons for their improved performance. The rats which experienced early maternal separation had enhanced production of neurons in the hippocampus — the part of the brain where memories are formed — and increased levels of a protein — called brain-derived neurotrophic factor (BDNF) — in the brain that aids production of neurons.

As if to compensate, the production of neurons and BDNF declined when the rats hit middle age, reducing memory capabilities. However, the scientists found that the adverse effects are not very alarming and could be reversed by treating the animals with a commonly available drug.

Vaidya admits that the study on animals, however, does not necessarily reflect the real picture. Stress is known to precipitate depression in humans. Scientists, however, have always known that psychiatric disorders such as depression are brought on only by a combination of two strong components – genetic as well as environmental. It is the interaction between the two that decides whether there is a possibility of one developing a psychiatric disorder. One major take-away from the new study is that stress is not necessarily bad for you; it can also make you resilient.

Vaidya, who is interested in finding out how life experiences modify brain circuitry, says stress also seems to precipitate some positive changes in the brain areas that are directly involved in handling stressful conditions such as the frontal cortex and the hippocampus. “It’s like leaving a signature of life history in the brain. So when a second experience comes, it doesn’t happen on a blank slate as the slate is already carrying information about the previous incident,” she remarks.

An earlier study by Vaidya’s team was equally significant. Their studies made it possible to improve the efficiency of anti-depressants. “Antidepressants take really long to work. They take weeks and months to show any effect. Think about it: here’s a person who is severely depressed and has suicidal tendencies. He has gone to a doctor and been given medication but this medication is unlikely to work for weeks,” she explains, pointing out the danger.

“We wanted to know why antidepressants take a long time to act. We seem to have some answers,” she says. A paper from Vaidya’s lab, published in the Journal of Neuroscience two years ago, reported that combining an antidepressant with certain brain chemicals significantly improved the performance of the medication, bringing early relief.

Only time will tell whether her new research too has such clinical impact.